Non-trivial length dependence of the conductance and negative differential resistance in atomic molecular wires
arXiv:0808.1494 · doi:10.1088/0957-4484/19/45/455203
Abstract
We study the electronic and transport properties of two novel molecular wires made of atomic chains of carbon atoms (polyynes) capped with either, benzene-thiols or pyridines. While both molecules are structurally similar, the electrical conductance of benzene-thiol-capped chains attached to gold electrodes is found to be much higher than that of pyridine-capped chains. We predict that the conductance is almost independent of molecular length, which suggests that these molecules could be ideal molecular wires for sub-10 nm circuitry. Both systems exhibit negative differential resistance (NDR) but its origin and characteristics depend on the type of molecule. We find a novel type of NDR mechanism produced by the movement of the LUMO resonance with bias. We also show that by gating the pyridine-capped molecules it is possible to make the NDR disappear and dramatically modify the - characteristics and the length dependence.
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